Part 26

_Var. nitidus_: with respect to this variety I have little to add to my preliminary remarks on its peculiar appearance, owing to its smooth, naked condition, and pure white or pale purple colour. This colour, when examined through a lens, is seen to consist of very fine longitudinal stripes; and is produced by the calcareous matter within the longitudinal parietal pores being thus coloured. Generally the scuta have two longitudinal furrows; but I have seen a scutum of one perfectly characterised specimen with only a single broad furrow, like that which frequently occurs in the membrane-covered variety. _Var. Coquimbensis_, as before stated, differs only in its greater size: the scutum, in the one specimen examined, had two broad longitudinal furrows; neither it, nor the tergum differed from certain varieties now found on the coast of Chile.

17. BALANUS PERFORATUS. Pl. 5, fig. 1 _a_-1 _d_; Pl. 4, fig. 3 _a_-3 _c_.

BALANUS PERFORATUS. _Bruguière._ Encyclop. Meth., 1789, Tab. 164, fig. 12 _infra_.

LEPAS ANGUSTA. _Gmelin._ Syst. Naturæ, 1789.

---- ORE ANGUSTIORE. _Chemnitz._ Vol. viii, Tab. 98, fig. 835.

BALANUS CORNUBIENSIS CONICO ORE MINORE. _Ellis._ Phil. Trans. vol. 50, 1758, Tab. 34, fig. 16.

LEPAS BALANUS ET FISTULOSUS. _Poli._ Test. Siciliæ (1795), Tab. 4, fig. 5, Tab. 6, fig. 1.

BALANUS COMMUNIS. _Pulteney._ Dorset Catalogue, 1799.

---- ---- _Montagu._ Test. Brit., 1803.

LEPAS ANGUSTATA. _Wood._ General Conchology, 1815, Pl. 6, fig. 5.

BALANUS CRANCHII. _Leach_ (!). (_B. Blainvillii_ in Tab.) Encyclop. Brit. Suppl., vol. iii, 1824.

---- ---- _Brown._ Illust. Conch., 1827, Pl. 7, fig. 9, 10, and 2d Edit., Pl. 53, fig. 9-12.

---- PERFORATUS. _Chenu._ Illust. Conch., Tab. 3, fig. 9, Tab. 6, fig. 15.[92]

[92] I have very little doubt regarding any of these references: I have no means of ascertaining the priority, within the same year, of Gmelin and Bruguière, but have given it to the latter, as _perforatus_ is much the best known specific name. English conchologists seem generally to suppose that the _B. communis_ of Pulteney and Montagu is the _B. porcatus_ of this work; but I have not the smallest doubt that I have given it rightly as a synonym of the present species; the indistinctness of the compartments, the multitude of fine ridges, the smallness of the orifice, the longitudinal furrow on the terga, the colour, size, and habitat, all given by Pulteney or Montagu, will agree with no other British species. The _Lepas balanus_ of Poli, which is certainly a synonym of our present species, has been erroneously considered by several authors to be the same with the _L. balanoides_ of Poli, which latter undoubtedly is the _B. amphitrite_ of this work.

_Shell pale purple, or white, or dirty ash-colour; smooth, or, from being corroded, finely ribbed longitudinally; sheath purple; orifice generally small; radii generally narrow or absent. Scutum, internally, with a short minute ridge, parallel and close under the prominent adductor ridge. Tergum with the apex somewhat produced._

_Var._ angustus (_Gmelin_) Pl. 5, fig. 1 _a_: _pale dull purple or white; orifice small or of moderate size; radii very narrow or moderately wide, white or pale purple, with oblique summits_.

_Var._ Cranchii (_Leach_) Pl. 5, fig. 1 _b_: _corroded, covered with fine longitudinal ridges owing to the exposed, filled-up, parietal tubes; dark dirty ash-colour, with a tinge of purple: radii not developed, or very narrow with oblique summits; orifice small_.

_Var._ fistulosus (_Poli_) Pl. 5, fig. 1 _d_: _shell cylindrical, white or dull purple; orifice of moderate size or small; basis deeply cup-formed_.

_Var._ mirabilis, Pl. 5, fig. 1 _c_: _bright purple; radii white, very broad, with their summits parallel to the basis; orifice entire, large_.

_Hab._--Southern shores of England; South Wales; Mediterranean; Western Africa, southward to Loanda, in 9° S.; West Indies (?). Generally adhering to rocks at a low tidal level; in one case attached to the floating _Lepas Hillii_, Mus. Jeffreys.

This is a well-marked species, and in its essential characters does not vary much; but owing to the shell being almost as often white as purple,--to its being remarkably subject to disintegration,--to its often becoming cylindrical,--to the radii being either not at all, or slightly, or moderately, or largely developed, and consequently to the orifice of the shell varying in size, the general external appearance of the different varieties is singularly diversified; but when a series of specimens is examined, it is easy to see how one form passes into another.

_General Appearance._--Shell conical, with the orifice oval, unusually small, being generally only from one third to half of the basal diameter; sometimes moderately large; in one single instance as wide as the basis. Radii, often represented by mere lineal fissures, or they are narrow, or sometimes moderately wide. Colour pale, dull purple, sometimes lilac, often passing into a dead pure white: the same individual will occasionally have one part of its shell white, and another purple: the purple tint almost invariably is nearly uniform, or not in stripes. The radii are generally white, when the whole shell is purple, but sometimes they are pale purple: the sheath is apparently always coloured of a fine claret-purple, with the triangular portion of the alæ, added during diametric growth, generally white, but sometimes purple. The surface is quite smooth, but very often, especially on the shores of England, whole groups of specimens (excepting the very young ones,) have had the outer lamina of the parietes entirely corroded and removed; in this case the shell assumes a dirty, more or less dark, ash-colour, feebly tinted with purple, and the whole surface, owing to the exposure of the solidly filled-up parietal tubes, becomes finely striated, or covered with very narrow, longitudinal ridges. When specimens are crowded together they often become cylindrical, and much elongated, owing to the basis becoming deeply cup-formed: I have seen specimens, half an inch in diameter in the widest part, one inch and a half in height, the walls forming only a third of this. The largest specimen which I have seen (from the southern shores of England) had a basal diameter of 1.2 of an inch; some very steeply conical specimens were .9 of an inch in height, and .8 in basal diameter.

_Scuta_, externally, slightly convex; growth-ridges approximate, moderately prominent. Internally (Pl. 4, fig. 3 _a_) the articular ridge is moderately developed, with the lower end produced downwards into a freely depending, flattened style, somewhat variable in size, but not so long as in _B. lævis_, and easily broken in disarticulating the valves. The adductor ridge is very prominent, running from almost the apex of the valve, close to the articular ridge, to near the basal margin. The basi-tergal portion of the valve is converted by the adductor ridge into a rather deep cavity, within which there is a short, sharp, and minute ridge, close and parallel to the adductor ridge, and bounding the impression left by the lateral depressor muscle: this insignificant ridge was present in every specimen; it occurs only in very few other species, as in _B. nubilus_ and _cariosus_. The thickness of the valve sometimes varies a little, and when thick the adductor ridge does not appear quite so prominent. _Tergum_, with the apex moderately beaked and produced; beak triangular in section, coloured dark purple, as is the upper internal surface of the valve; the longitudinal furrow is deep, and has its edges folded in, and even quite closed. The spur is moderately long and narrow; but its width varies a little (Pl. 4, fig. 3 _b_, 3 _c_), and consequently it stands at either rather above or at twice its own breadth from the basi-scutal angle: its lower end is either bluntly pointed or square, and generally is feebly toothed on the under-side. The basal margin of the valve generally slopes a little, on both sides, towards the spur. Internally, the scutal margin is but slightly inflected: the articular ridge is but slightly prominent, and but little curved; in the upper part of the valve there are generally several very minute ridges, parallel to the articular ridge, on the side towards the scutum. The internal surface of the spur itself is sometimes concave. The crests for the carinal depressor muscle are barely developed. It may here be mentioned that on the opercular membrane many long spines stand rudely arranged in rows.

_Parietes_: the parietal tubes have not transverse septa; but are solidly filled up in their upper parts by dark-purple layers of shell. The _radii_, as already stated, are either not at all developed, or are extremely or only moderately narrow, with their summits more or less oblique: in Mr. Cuming's collection, however, there is an unique specimen, _var. mirabilis_ (Pl. 5, fig. 1 _c_) with the aperture of the shell as wide as the basis, with bright purple parietes, and white, very broad radii, having their summits parallel to the basis. The septa of the radii are finely denticulated, and the interspaces are filled up solidly. The _alæ_ have very oblique summits, and their edges are finely crenated. _Basis_, flat, or deeply cup-shaped; there is often an underlying, coarsely-cancellated layer.

_Mouth_: labrum finely hairy, but without any teeth; mandibles, with the 4th tooth small; the 5th confluent, with the sometimes smooth, sometimes pectinated inferior angle. Maxillæ, rather broad, with a slight notch under the upper pair of spines. _Cirri_, first pair, with one ramus, having 29 segments, and above one third longer than the shorter ramus, having 17 segments; these latter segments are remarkable by the extent to which their upper front surfaces are laterally produced into projections, twice as long as the breadth of that portion of the segment which is articulated to the adjoining segment. These projections have a double row of serrated spines on their upper edge, and a beautiful radiating bundle at the end; the projections decrease in length, both in the upper and lower segments. The second cirrus (Pl. 29, fig. 4) has the segments (13 in number, in the same individual with the segments above enumerated) of both rami produced in the same singular manner as in the first pair. The third pair have only inverted conical segments, coloured darker purple than the other cirri. The sixth pair had in the same individual 31 or 32 segments, and therefore one or two more than in the longer ramus of the first pair.[93] The segments in the posterior cirri have their anterior faces shield-shaped, and bear 6 or 7 pairs of spines, with some minute intermediate spines. There is the usual point at the dorsal basis of the penis.

[93] Under the Genus (p. 190) I have given the numbers of the segments in the cirri of this species at successive ages.

_Range._--This species is common on the southern shores of England and in the Channel Islands: the largest specimens which I have seen came from these quarters. The most northern point whence I have seen specimens, is Tenby, in South Wales. This species is common throughout the Mediterranean; I have seen specimens from Malaga, Sicily, Algiers, and Smyrna; thence it ranges down the western coast of Africa, as far south as the Gambia and Loanda, in 9° south latitude. I believe British specimens are more often corroded than those from further south. Amongst some old, ill-kept specimens in a box in the British Museum, marked "Kingston, Jamaica," there were some of this species: also I received some specimens, marked "S. America," from Mr. G. B. Sowerby: again, Ellis, in Phil. Trans., vol. 50, part 11, gives a figure (Tab. 34, fig. 15) of some specimens from the West Indies, which I believe to be _B. perforatus_: hence, it is in some degree probable that this species, like _B. tintinnabulum_, and _amphitrite_, and _improvisus_, may be found on both sides of the equatorial Atlantic. _Balanus perforatus_ is attached, together with _B. tulipiformis_, _trigonus_, _amphitrite_, _Chthamalus stellatus_, and _Pollicipes cornucopia_, usually to rocks, near the lower limit of the tidal level; but I believe, from specimens kindly sent me by Mr. Mac Andrew, that it is frequently obtained by dredging; one specimen was even marked 30 fathoms. According to Poli, it is sometimes attached to the bottoms of vessels; and I have seen a specimen adhering to the floating _Lepas Hillii_.

_Affinities._--This is a distinct species, closely allied to no other species, but comes nearest to _B. lævis_, which is its representative in Southern America, and on the whole west coast of that continent. It is allied to that species, and differs from most other species, in the general form of the shell, its small orifice, narrow radii, and often deeply cup-formed basis. It agrees to a certain extent in the colouring, though the purple here is much more prevalent, and is not confined to the shelly matter filling up the parietal tubes. It agrees with that species in the general structure of the scutum; but the two or three deep, longitudinal furrows are here absent; and the minute ridge, parallel to and almost under the adductor ridge, is a peculiarity confined to this and very few species in the genus. The terga differ from those of _B. lævis_, chiefly in the spur being narrower, and in the apex being beaked. Lastly, the highly protuberant segments of the one ramus in the first cirrus, and of both rami in the second pair, are here remarkable. With regard to the varieties, I have nothing to add to their short diagnostic characters above given.

18. BALANUS CONCAVUS. Pl. 4, fig. 4 _a_-4 _e_.

BALANUS CONCAVUS. _Bronn._ Italiens Tertiär-Gebilde (1831) et Lethæa Geognostica, b. ii, s. 1155 (1838), Tab. 36, fig. 12.[94]

---- CYLINDRACEUS, _var._ c. _Lamarck._ Animaux sans Vertèbres (1818).

LEPAS TINTINNABULUM. _Brocchi._ Conchologia Sub-Appen., t. ii, p. 597 (1814).

[94] I suspect that _B. pustularis_, _miser_, and _zonarius_, all figured by Münster, in his 'Beiträge,' b. iii, Tab. 6, may be this species.

_Shell longitudinally striped with white and pink; or dull purple; sometimes wholly white. Scutum finely striated longitudinally; internally, adductor ridge very or moderately prominent._

_Hab._--Panama; Peru; S. Pedro in California; Philippine Archipelago; Australia. Mus. Brit., Cuming, Stutchbury, Aug. Gould.

_Fossil_ in Coralline Crag, England; Mus. Brit., S. Wood, Bowerbank, Lyell, J. de C. Sowerby, Tennant. Sub-Appennine formations, near Turin, Asti, Colle in Tuscany, Mus. Greenough, &c. Tertiary beds, near Lisbon, Mus. D. Sharpe and Smith. Bordeaux (?) Mus. Lyell. Tertiary beds, Williamsburg; and Evergreen, Virginia, Mus. Lyell. Maryland, Mus. Krantz. Recent formations[95] near Callao, Peru, Mus. Darwin. Red Crag (Sutton) Mus. S. Wood.

[95] I procured this specimen from the Island of S. Lorenzo, off Callao; it was imbedded, together with seventeen species of recent shells and with human remains, at the height of eighty-five feet.

This species has caused me much trouble. Looking first to the recent specimens, I examined several from Panama and California, which, though differing greatly in colour, resembled each other in their scuta having the adductor ridge extremely prominent, and in having (Pl. 4, fig. 4 _a_), an almost tubular cavity for the attachment of the lateral depressor muscle,--characters which at first appeared of high specific value; but I soon found other specimens from Panama in which these peculiarities were barely developed. I then examined a single specimen from the Philippine Archipelago, resembling in external appearance one of the Panama varieties, but differing in the scuta being externally strongly denticulated in lines instead of being merely striated,--in the adductor ridge being far less prominent,--and in the spur of the tergum being broader and more truncated; I therefore considered this as a distinct species. I then examined a single white rugged specimen from the coast of Peru, which differed from the Philippine specimen in the shape of the well-defined denticulations on the scuta, and in some other trifling respects, and in the segments of the posterior cirri bearing a greater number of spines; with considerable doubt, I also named this as distinct. But when I came to examine a large series of fossil specimens from the Coralline Crag of England, from northern Italy, from Portugal, and from the southern United States, I at once discovered that the form of the denticuli on the scuta was a quite worthless character,--that in young specimens the scuta were only striated,--that the prominence of the adductor scutorum ridge and the depth of the cavity for the lateral depressor muscle varied much (as in the case of the recent specimens), owing apparently to the varying thickness of the valve,--that in the terga the spur varied considerably in length and breadth, the latter character being in part determined by the varying extent to which the edges of the longitudinal furrow are folded in,--and lastly, that in young specimens the basal end of the spur is much more abruptly truncated than in the old. Hence I have been compelled to throw all these forms, originally considered by me as specifically distinct, into one species. I must repeat that this considerable variation in the prominence of the adductor ridge, and in the depth of the pit for the lateral depressor muscle--the pit in some cases becoming even tubular--is a very unusual circumstance.

With respect to the fossil specimens[96] from the above-stated several distant localities, I consider them as certainly belonging to one species, though varying considerably in several points of structure. When compared with the recent specimens, they differ from them in often attaining a considerably larger size; in the parietes being often, but not always, longitudinally ribbed; and in the radii often having more oblique summits. On the other hand, considering the many points of identity between the fossil and the recent specimen, I have concluded, without much doubt, that they ought all to be classed together. I may remark that, in the Coralline Crag specimens, the spur of the tergum (Pl. 4, fig. 4 _d_), is unusually long and narrow; it is broader and shorter in the Italian specimens (4 _e_), and variable in this respect, in the United States specimens; the scuta of the Lisbon specimens are remarkable for the greater prominence of the adductor ridge, and for the depth of the lateral depressor cavity. Some of the specimens from all the several localities are identical with the recent ones from the coast of Peru. The walls of the shell in the Coralline Crag specimens, are generally ribbed longitudinally. I have entered into the above particulars, on account of, in the first place, its offering an excellent example how hopeless it is in most cases to make out the species of this difficult genus without a large series of specimens; secondly, as showing how the characters alter with age; and thirdly, as a good instance of the amount of variation which seems especially to occur in most of the species which have very extensive ranges.

[96] These will be fully illustrated in the monograph on the Fossil Balanidæ, to be published by the Palæontographical Society.

Some of the pink-striped Panama varieties, though having a somewhat different aspect, can be distinguished from certain varieties of _B. amphitrite_ only by their scuta being longitudinally striated,--a character in this species variable in degree, and in most cases of very little value. Some of the other recent varieties are sufficiently distinct from _B. amphitrite_; and the great fossil Coralline Crag specimens, which stand at the opposite end of the series of varieties, with their ribbed walls, very oblique radii, and coarsely striated scuta, are extremely unlike _B. amphitrite_. With respect to the nomenclature of the present species, I have little doubt that I have properly identified the Italian fossil specimens with _B. concavus_ of Bronn, who has given a very good figure of this species in his 'Lethæa Geognostica;' it must, however, be confessed that the longitudinal striæ on the scuta are not there represented. Considering the large size and frequency of this species in Europe and in the United States, it has probably received several other names, besides the two incorrect synonyms, quoted at the head of this description. I should add that the true _B. cylindraceus_ (not _var._ C) of Lamarck, according to the plate given by Chenu in his 'Illust. Conch.,' is the _B. psittacus_ of South America. I have seen in collections specimens of _B. concavus_ labelled as _B. tulipa_ of Poli (_B. tulipiformis_ of this work),--a very natural mistake, without the opercular valves be carefully examined.

_General Appearance._--Shell conical, often steeply conical; orifice rather small, with the radii narrow, and generally in the fossil specimens very oblique; surface generally smooth, sometimes rugged, and in the coralline crag specimens generally ribbed longitudinally, the ribs being narrow. Colour various, either dull reddish-purple with narrow nearly white, or wider dark longitudinal bands; or, again, pale rosy-pink with broad white bands; or lastly, wholly white. The radii are either darker or paler than the parietes. The opercular valves are either dark purple or nearly white. Pale pink and white stripes are visible on some of the Italian and Portuguese tertiary specimens; and in most of the fossils the sheath is tinged dull red.

_Dimensions._--The largest actually recent specimen which I have seen, from the Philippine Archipelago, had a basal diameter of 1.2 of an inch; the Peruvian pleistocene specimen is 1.7 in diameter; specimens from the crag and from the Italian deposits, however, sometimes slightly exceed two inches in basal diameter, and three in height.